The invention relates to methods for separating rennet components and, more particularly, to methods for separating substantially pure chymosin from low quality rennet extracts or the like and using same to adjust the chymosin content of milk clotting enzyme-containing materials to a predetermined level.
Rennet derived from animal tissue, such as the fourth stomach (abomasum) of bovine animals, includes two milk clotting enzymes, chymosin and bovine pepsin. The relative concentration of these two enzymes varies widely depending primarily on the age of the animal at the time of slaughter and/or its diet. For instance, rennet derived from young suckling calves less than 60 days old typically is composed primarily of chymosin, while that derived from an adult animal is composed primarily of bovine pepsin.
When used in the production of cheese, rennets having a high chymosin content generally produce higher yields and superior flavor and texture characteristics. Variations in the chymosin content require changes in the amount of rennet used in order to maintain the same yield and cheese quality. The availability of high chymosin rennet is becoming more limited because of a reduction in the number of calves slaughtered.
IDF Standard 110:1982 describes a chromatographic method for determining chymosin and bovine pepsin content in rennet extracts. Chymosin and pepsin are first applied to a diethylaminoethyl (DEAE) cellulose resin. Sodium chloride solutions of different concentrations are then sequentially passed through the column to obtain a first fraction containing chymosin and a second fraction containing pepsin.